The invention relates to an extrusion machine, particularly for the extrusion of chemical granular material, preferably for detergents, having a machine frame, an extrusion press with a material inlet opening and a material outlet opening, a drive for the extrusion press and a die provided in the vicinity of the material outlet opening and a cutting tool associated with said die.
In such known extrusion machines the die is fitted in stationary manner to the extrusion press. The cutting tool is also stationary with respect to the extrusion press. During production with the extrusion press it is necessary at certain intervals to replace the die and/or the cutting tool. For this purpose it is necessary to stop the extrusion press, so that the production process is interrupted. Production must then be started up again after replacing the die or the cutting tool. However, this starting process initially leads to a certain production wastage until the production process has been so readjusted as to obtain the desired quality.
For the extrusion of detergents there are e.g. production processes in which initially dry materials are weighed and are then transported over several floors to a mixer, where various liquids are added to the pulverulent materials. The mixture is then supplied to the extruder. If the production process has to be interrupted as a result of a replacement of a die or a cutting tool on the extruder, a dry product batch remains in the mixer. On recommencing the production plant this dry product must initially be discharged upstream of the extruder, because otherwise the dry product would block the extruder screw. Therefore initially the mixing process must be started up until the mixer supplies a desired extrudable initial product. Before the mixture supplied by the mixer is sufficiently plastic, several hundred kg of material are discharged upstream of the extruder. The checking of the mixture delivered by the mixer normally takes place manually and is therefore very time and labour-consuming. If this preliminary work is not conscientiously carried out during the restarting of the extrusion machine, it is necessary to clean all the product-carrying members of the extruder.
Therefore a replacement of a die or cutting tool in such an extrusion machine not only leads to production losses during the changing operations, but also to a considerable production loss on restarting the extrusion machine.